Membrane and Desalination Technologies - TCE Moodle Website

256 L.K. Wang et al.
Salty Cheese Whey
NaCl 1,200 kg
Whey Solids 1,200 kg
Total 20,000 kg
Desalted Whey
NaCl 65 kg
Whey Solids 1,032 kg
Total 5,000 kg
Permeate
Cream
Cream
Separator
Removal of salts from a food processing water stream can also be accomplished by using
ED or ion exchange; however, the capital costs of both ED and ion exchange are higher than
that of NF.
5.4. Recovery of Potato Starch Effluent Using RO
UF
NaCl 1,135 kg
Whey Solids 168 kg
Total 25,000 kg
Balance
Tank
Water for
Ultrafiltration
10,000 kg
For Disposal
Fig. 6.15. Removal of salts from cheese whey permeate by NF.
Clean-in-place
Tank
The Avebe Foxhol plant in the Netherlands produces starch from potatoes (34). As shown
in Fig. 6.16, potato production involves washing and grinding potatoes to produce pulpy
liquor containing potato water, starch, and fibers. The starch is then extracted, refined, and
dried as a product. The starch extraction effluent is treated by centrifugation for the separation
of fibers. The residual effluent from the centrifuge contains protein, sugars, and minerals at
about 4% TS previously too dilute to recover. The plant originally discharged its 180 m 3 /h of
effluent into the North Sea and Holland’s canals without treatment, causing serious water
pollution.
A continuous RO cleaner production system is now operated at Avebe utilizing openchannel
tubular RO membranes for handling of high TSS in the centrifuge effluent. With the
continuous RO system (34–36), the centrifuge effluent is divided into two streams: (a) the RO
permeate amounting to about 90 m 3 of water; and (b) the RO retentate having 8% TS and
about 90 m 3 of water. The RO permeate is recycled to the grinding operation for reuse, while
the RO retentate is treated by steam heat, coagulation, and mechanical separation, which is
then dried as a high grade protein concentrate (protomyl PF) that can be used as animal feed
for small animals, such as piglets, poultry, dogs, cats, minks, etc. The residual potato water
from mechanical protein separation is evaporated, concentrated to about 60% TS, and